The present invention relates to binocular magnifying glasses which are worn for examining an object in a magnified manner when performing precision work by hand, etc.
In conventional binocular magnifying glasses of this type, there has been known the technology disclosed in Japanese Patent Provisional Publication No. HEI 7-199083. The binocular magnifying glasses have a pair of magnifying optical systems, each system being provided for each of the right and left eyes. Each magnifying optical system includes an objective lens having a positive power and an eyepiece having a negative power arranged in that order from an object side to an eye side. Optical centers of the objective lens and the eyepiece of each magnifying optical system are positioned outside a line connecting the center of rotation of the eye and the object point as shown in FIG. 1 of the publication.
With this configuration, the binocular magnifying glasses providing a balance between accommodation and convergence of the eyes can be attained. However, there is a problem that the wearer is required to lean his or her head by an angle raging from 30° to 60° with respect to a horizontal direction because an optical path of each of the magnifying optical systems for the right and left eyes is a straight line. Therefore, the wearer is not able to withstand long-term use of the binocular magnifying glasses.
When the optical path in each of the magnifying optical systems for the right and left eyes is bent by an angle range of 30° through 60° so as to reduce the burden on the wearer, an additional problem occurs. That is, when the optical axis of each of the magnifying optical systems is bent, if the magnifying optical system is tilted to adjust the convergence of the eyes, right and left images rotate in directions opposite to each other. In such a case, even if the adjustment of convergence is accomplished, the right and left images do not match with each other.